Platelet-derived growth factor (PDGF) may stimulate proliferation of cells which lead to the development of various proliferative retinopathies. Furthermore, PDGF may be especially important in regulating the regrowth of membranes following initial therapeutic surgery. Thus, it has been hypothesized that measurement of PDGF levels in the proliferative membrane removed during surgery could: (1) predict the likelihood of recurrence; and (2) allow special intervention to prevent recurrence in high-risk situations. We propose using a DNA hybridization method that has been established to be suitable for the rapid analysis of paraffin- embedded historical specimens. This method has been used successfully to detect mRNAs of several retinal proteins (opsin, S-antigen). The goals of Phase I are: 1) to demonstrate the feasibility of using a simple and sensitive non-radioactive procedure to identify and localize the sites of production of PDGF; and (2) demonstrate the feasibility of gathering data on the correlation of PDGF expression with several proliferative retinal disorders. Upon meeting these objectives, a Phase II study would include a larger scale retrospective analysis on the pathophysiology of these disorders.